We don’t want to foster a lot of vigorous vegetative growth, since that increases the chance of winter damage and it also reduces flowering and fruit production.

If some fertilizer intended for adjacent plants spills toward them incidentally, no big problem.

Dear Neil: What is causing sticky sap to drip from our huge live oak? We’ve had the tree for 25 years, and this is the first time.

Answer: There have been a lot of instances of aphids on oaks this late summer and early fall.

At this point in the season, it’s difficult to make a case for spraying them. Rains will wash many off, and their activity will slow.

However, you could use a general-purpose insecticide with a high-pressure sprayer to reach them if you wished.

Dear Neil: If I want to prepare a raised bed for a perennial garden that I’ll start planting this fall, how high should I elevate it? Are there places where I wouldn’t need to have a raised garden?

Answer: Your goals with any raised garden will be either to display the plants more visibly or, more commonly, to ensure perfect drainage in times of prolonged wet weather.

There are parts of Texas where they’ve not used the term “prolonged” in reference to wet weather in many years, so those drier areas wouldn’t see the benefit of the improved drainage.

But, people gardening in heavy clay soils and in wet parts of Texas or at the bottoms of hills would be advised to prepare beds that are 4 to 6 inches above the surrounding grade (more if needed). That will allow soil-borne water to drain away to lower ground after rains and irrigation.

My old theory has always been that you can always add a bit more water. It’s much more difficult to get excess water out of the ground.

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